Marines (from the English adjective "marine," meaning "of the sea," from Latin language "mare," meaning sea, via French adjective "marin(e)," "of the sea") are, in principle, seaborne land soldiers that are part of a navy. However, in some countries, Marines are no longer part of the navy, notably the United States Marine Corps, which has become an independent armed force falling only administratively under the navy.
I don't think that they are even administratively under the Navy. Their association with the Navy, nowadays, is as security. The Marine Corps has its own Commandant which I believe ranks up with the Navy, Air Force and Army's highest officers.
I stand a little bit corrected:
The United States Marine Corps (USMC) is a branch of the U.S. military responsible for providing power projection from the sea, utilizing the mobility of the U.S. Navy to rapidly deliver combined-arms task forces to global crises. Alongside the U.S. Navy, the Marine Corps operates under the United States Department of the Navy.
The Marine Corps, with 180,000 active duty and 40,000 reserve Marines as of 2005, is the smallest of the United States' armed forces in the Department of Defense.
the marines is a branch of the navy
they are on their own..
its them the army navy and armed forces
the marines are the mens department of the navy.